The Skyactiv 2 gasoline and diesel engines will focus on improved internal combustion, said Mitsuo Hitomi, executive officer in charge of powertrain development, during a briefing at Mazda’s Yokohama technical center. The focus will be on lean burning, and increased compression ratios for the gasoline engines. The engines, according to the report, will use homogeneous charge compression ignition (HCCI).
Mazda engineers aim to eke the gains by cranking up the engine’s compression ratio to 18:1, from a current level of 14:1. Higher compression tends to improve fuel economy because they can achieve the same combustion temperature with a leaner mix of fuel. Mazda says the 14:1 ratio in its first-generation Skyactiv gasoline engine is the world’s highest.
Hitomi also outlined plans for a Skyactiv 3 lineup further in the future that would limit the fluctuation of heat in the combustion chamber to reduce losses from exhaust and cooling. The goal is achieving well-to-wheel carbon dioxide emissions on a par with electric vehicles.